Friction device for hydrodynamic unit rotor

ABSTRACT

Hydrodynamic torque converter in which the stator is mounted on a cone-type friction device having a first cone member fixed to a ground sleeve and a second cone member which carries the stator. The second cone member is supported on the first cone member and is moved into and out of frictional engagement in accordance with the flow conditions within the converter. At stall and up to coupling, the flow of fluid through the converter acts on the front faces of the stator blades to provide a force which effects the frictional engagement of the friction device so that the stator is grounded to provide for reaction and torque multiplication. As turbine speeds increase to pump speed, the fluid exiting from the turbine flows against the rear faces of the stator blades removing the apply force allowing the stator to freewheel so that the converter operates as a fluid coupling.

United States Patent Welch et al.

3,724,208 Apr. 3, 1973 FRICTION DEVICE FOR HYDRODYNAMIC UNIT ROTORPrimary Examiner-Edgar W. Geoghegan Attorney-W. E. Finken, A. M. Heiterand Charles R.

, White [57] ABSTRACT Hydrodynamic torque converter in which the statoris mounted on a cone-type friction device having a first cone memberfixed to a ground sleeve and a second cone member which carries thestator. The second cone member is supported on the first cone member andis moved into and out of frictional engagement in accordance with theflow conditions within the converter. At stall and up to coupling, theflow of fluid through the converter acts on the front faces of thestator blades to provide a force which effects the frictional engagementof the friction device so that the stator is grounded to provide forreaction and torque multiplication. As turbine speeds increase to pumpspeed, the fluid exiting from the turbine flows against the rear facesof the stator blades removing the apply force allowing the stator tofreewheel so that the converter operates as a fluid coupling.

4 Claims, 4 Drawing Figures FRICTION DEVICE FOR HYDRODYNAMIC UNIT ROTORThis invention relates to hydrodynamic torque transmitting units andmore particularly to a friction device advantageously utilizing fluidflow forces occurring within a hydrodynamic unit for connecting anddisconnecting a unit rotor and a ground member.

One-way friction devices have been employed in hydrodynamic torqueconverters to prevent rotation of the stator in one direction so thatthe stator will be stationary and provide the reaction allowing theconverter to multiply input torque. As the turbine speed increases up topump speed, the fluid flow within the converter changes in a manner toeffect the release of the oneway device so that the stator overruns toprovide a coupling phase of operation.

Prior to the present invention, roller or sprag type one-way deviceshave usually been employed in torque converters to automatically connectand disconnect the stator and the ground sleeve. While these one-waydevices have been completely satisfactory in operation, they employ alarge number of precision made components such as rollers or spragswhich work in inner and outer races. These one-way devices are expensivesince they have to be made with special metals and to close tolerances.Prior attempts to replace these oneway friction devices with alternativedevices have met with only limited success since they usually involvecostly and complex arrangements and often their performances are not asgood as the roller and sprag type devices.

With this invention, the conventional one-way device such as sprag androller one-way units can be readily replaced by a two-piece cone typefriction device that is released and engaged in accordance with thefluid flow conditions within the converter. In the preferred form ofthis invention a first cone clutch is fixed to the ground sleeve of atorque converter and a second cone clutch which carries the statorelement is rotatably and slidably mounted on a shoulder of the firstcone clutch. From stall up to coupling, the oil flow through theconverter acts on the front face of stator blades to bias the secondcone clutch into clutching engagement with the first cone clutch. Underthese conditions the stator element will be grounded for reaction andthe converter multiplies input torque. As turbine speed increases andapproaches the speed of the pump, the oil leaving the turbine flowsagainst the rear face of the stator blades thereby removing the clutchapply force. This allows the second cone clutch element and the statorto revolve freely on the first cone clutch element and in the directionof the rotary flow of converter oil so that the converter operates as afluid coupling.

It is an object of this invention to provide a new and improved flowcontrolled friction device for grounding and releasing a rotor in ahydrodynamic torque transmitting unit.

Another object of this invention is to provide a new and improvedfriction device for a torque converter stator which incorporates a pairof cone friction members controlled by the flow of oil within theconverter; the cone members are relatively moved longitudinally intoclutching engagement under predetermined oil flow conditions within theconverter so that the stator is grounded permitting the converter tomultiply torque. Subsequently, as turbine speed approaches pump speed,the oil flow changes to effect release of the friction members so thatthe stator can freewheel permitting the converter to function as a fluidcoupling.

Another object of this invention is to provide a torque converter inwhich the stator is mounted on a new and improved cone-type frictiondevice that incorporates a minimum number of parts and is automatic inoperation being engaged and released in accordance with the fluid flowconditions within the converter, to produce optimum efficiency ofconverter operation during coupling.

Another object of this invention is to provide a new and improvedone-way locking device for a bladed rotor in a hydrodynamic unit which(1) makes advantageous use of hydrodynamic thrust forces occurring onthe blades of the rotor during operation of the hydrodynamic unit tolock the device so that the rotor is held from rotation and (2)eliminates triggering mechanisms and parasitic drag present in otheroneway locking devices when the rotor is released for rotation by thelocking device.

These and other objects of the invention will become more apparent fromthe following drawings and detailed description in which:

FIG. 1 is a side sectional view of a hydrodynamic torque converterillustrating one embodiment of the invention. 1

FIG. 2 is a side sectional view of a hydrodynamic torque converterillustrating another embodiment of the invention.

FIG. 3 is an exploded view of the torque converter of FIG. 1 showing thepath of converter oil flow during the coupling phase of operation.

FIG. 4 are curves illustrating the operation of hydrodynamic torqueconverters.

As shown in FIG. 1 there is input lug 10 which is drivingly connected tothe front cover 12 of a hydrodynamic torque converter 14. The torqueconverter has a bladed pump 16 operatively connected to the housing 18driven through front cover 12, a bladed turbine 20 and a bladed statorassembly 22. This stator assembly 22 is mounted on a flow-controlledfriction device 24 that is operatively connected to a rounded sleeve 26,The stator assembly has inner and outer shrouds 27 and 28 between whichstator blades 30 are positioned at a predetermined angle as best shownin FIG. 3. The inner shroud of the stator is mounted on, and is securedto, the outer periphery of a first friction member or hub 40 of theflow-controlled friction device 24. This friction member has an innercylindrical sleeve 42 which slidably fits on an extending, cylindricalhub 44 of a second friction member or hub 46 of friction device 24 whichis splined to the grounded sleeve 26. As shown, the two friction membersare located between the annular spacers 47 and 49 disposed within theconverter, which function as bearings and spacers. In the disengagedposition shown, the first or rotary friction member 40 engages spacer 47to limit release or disengaging movement.

The first friction member 40 has an internal conical friction surface 48which can be moved from the disengaged position shown into matingengagement with an external conical friction surface 50 of the frictionmember 46. Also, there is an oil passage 52 formed through the side wallof friction member 46 to exhaust oil from the cavity 54 formed by thetwo friction members when the members are being engaged.

Oil is fed into the converter through supply passage 55 and inletpassages 57 in spacer 49. Oil is discharged from the converter throughradial discharge passages 59 in spacer 47 into return passage 61.

The turbine 20 is drivingly connected to a disc-like hub member 60 whichis s'plined to the end of a driven shaft 62. This driven shaft extendsfrom the hub member rearwardly through the grounded sleeve 26 to asuitable gear unit or other drive mechanism not shown.

In operation the first friction member is movable into engagement withthe second friction member by a resultant axial force exerted byconverter oil on the front faces of the blades 29 of the stator assembly22. Assuming that the vehicle employing this converter is stationary andthe engine is started, the pump 16, driven by the engine, pumpsconverter oil into the stationary turbine 20. This oil flows through theturbine and is directed by the turbine blades into the front faces ofthe stator blades, which in turn direct oil back into the pump in adirection to assist pump rotation to thereby provide for convertertorque multiplication.

The resultant force exerted by this oil on the stator blades has anaxial force component which effects the limited axial movement of clutchmember 40 toward the clutch member 46 and the resultant lockingfrictional engagement of conical clutch surfaces 48 and 50. Under theseconditions the stator is held stationary and the converter multipliesinput torque. As the turbine begins to rotate to accelerate the vehicle,the angle of attack of oil leaving the turbine on the stator bladesgradually diminishes and finally is directed onto the rear faces of thestator blades as indicated by the fluid flow arrows A in FIG. 3. Whenthis occurs, the axial force effecting clutch engagement and thecapacity of the cone clutch are reduced to zero and the statorfreewheels in the forward direction as illustrated by arrow R in FIG. 3.Under these conditions the con verter functions as'a fluid coupling.This operation will continue until the turbine speed reduces to a speedless than pump speed and until the oil exiting from the turbine into thestator again is directed onto the front faces of the stator blades toeffect engagement of the clutch as described above.

FIG. 2 shows another embodiment of the invention which is similar to thefirst embodiment but employs a spring between the cone clutch members ofthe stator to provide a clutch release force to ensure that the clutchreleases at coupling without significant parasitic drag. Correspondingparts of the two embodiments are identified with the same referencenumerals with those of FIG. 2 being primed.

The torque converter 14' of FIG. 2 has bladed pump 16' driven throughconverter housing 18' and has a bladed turbine 20' and bladed statorassembly 22. The turbine drives shaft 62' through hub 60'. The statorassembly has blades 30' and is rotatably mounted on an annular bearing Bwhich is splined to or otherwise secured ground sleeve 26'. Also thestator assembly has a hub or friction member 40 formed with an internalcone clutch surface 48', which can be moved from the disengaged positionshown into mating engagement with an external conical surface 50' of thehub or friction member 46'. Member 46' is secured to the annular bearingB and is therefore grounded through the ground sleeve 26. An oil passage52', formed through the side walls of the member 46' is provided toexhaust oil from the cavity 54' between the two friction members as thefriction members are being moved into engagement. A waved and circularspring member 64' is disposed between the two members 40 and 46' toprovide a release force to assist the disengagement of the cone clutchat the coupling point. Asin the first embodiment, the converter isfilled with oil through inlet passage 26' and oil is discharged throughdischarge passage 59' and return passage 61'.

In operation the FIG. 2 device operates in a manner similar to thatdescribed in connection with the FIG. 1 construction. At stall and up tocoupling the axial force of the working fluid exerted on the statorblades causes the axial movement of the stator and the frictionalengagement of frictional surfaces 48' and 50' so that the stator isgrounded and held for reaction. In this embodiment the spring 64'opposes this movement, however, the engaging force at stall and up tocoupling is greater than the force of the spring so that the frictionsurfaces 48' and 50' are fully engaged. At coupling, when the axialforce has sufficiently diminished, the spring 64' effects the quickrelease of the friction surfaces 48' and 50' without parasitic drag.

In FIGS. 1 and 2, the differential between the pressure in the inletpassage and the outlet passage will, in typical torque converters wherethe inlet passage pressure is normally less, produce a resultant forcein an engaging direction but this force will also be reduced appreachingand in the coupling phase as the toric circulation is reduced. In thenormal torque converter, the above explained forces on the stator bladesprovide the major engaging force. The forces acting on the stator hubdue to the inlet and outlet pressure differential provide a lesserengaging force. Normally both of these forces act in the same direction.The net sum of these fluid forces and a spring force as shown in FIG. 2,which could be used in FIG. 1, on the complete axially movable statorassembly blades and the hub, is such that during the torquemultiplication phase the gradually decreasing clutch engaging force isprovided and just before or at initial coupling, these forcesautomatically release or are low enough to permit the fluid flow inducedrotational force on the stator blades to release the clutch to permitfreewheeling of the stator.

The operation of this invention is graphically illustrated in FIG. 4.Curve a is an efficiency curve of a converter using the presentinvention. In the torque-multiplying phase of operation up to thecoupling point 0, the stator is held for reaction by the cone clutch. Atstall, the hydrodynamic efficiency of the converter is zero since thereis no turning of the turbine. As the turbine accelerates from stall, theefficiency of the converter increases to an initial peak, i.e., percentas shown by point p. After this, the efficiency slightly decreases toLe, 87 percent until at coupling point c, the cone clutch releases thestator for rotation and the converter operates in the coupling phase.

It is important for high efficiency operation that freewheeling of thestator should not be held or resisted beyond the coupling point c. Thenet sum of the axial forces is reduced to zero at the same time as therotary reaction force is reduced to zero so the first small negativerotary reaction force on the stator can act on a completely free statorfor freewheeling of the stator without delay or resistance. The net sumof the axial forces also may reduce to zero just prior to the reductionof the rotary reaction force to zero. This would ensure that the statoris free as the rotary reaction force becomes zero and then negative sofreewheeling is immediately initiated with the first small negativerotary force on the stator.

After the stator is released, the efficiency again increases to a veryhigh efficiency to i.e., 97 percent. With this invention, frictionaldrag present in prior art devices using rollers, tickle springs andsprags, is minimized. Thus, this invention provides for improvement inconverter efficiency during the entire coupling phase of operation.Curves d and e are input speed and torque ratio curves for thisinstallation.

This invention is not limited to the details of the construction shownand described for purposes of illustrating the invention for othermodifications will occur to those skilled in the art.

What is claimed is:

1. In a hydrodynamic torque transmitting unit having a plurality ofbladed rotors which are rotatable about a longitudinal axis, an inputoperatively connected to a first of said rotors, an output operativelyconnected to a second of said rotors, a third of said rotors operativelydisposed in said unit between said first and second rotors, a groundsleeve extending into said unit, friction means for connecting anddisconnecting said third rotor and said ground sleeve, said frictionmeans comprising first and second friction members, said first frictionmember having a conical friction surface thereon and having a supportsleeve extending longitudinally therefrom, said second friction memberbeing mounted for rotary and longitudinal movement with respect to saidlongitudinal axis on said support sleeve, said second friction memberhaving a conical friction surface thereon for frictionally engaging saidfirst mentioned friction surface, connecting means for connecting saidsecond friction member and said third rotor so that the force ofconverter fluid circulating in said converter acting on said third rotorin a first operating condition will effect the limited longitudinalmovement of said second friction member in one direction and theengagement of said friction surfaces to thereby ground said third rotorand so that the friction surfaces disengage without substantial dragpermitting rotation of said third rotor in response to the removal ofsaid fluid forces as said second rotor reaches approximately the speedof said first rotor.

2. The torque transmitting unit of claim 1 and further comprising springmeans operatively disposed between said friction members for exerting anaxial force on said second friction member to cause the rapiddisengagement of said friction surfaces as the rotary speed of saidsecond rotor is substantially equal to the rotary speed of said firstrotor so that said third rotor is released for free rotation in saidhydrodynamic unit.

3. A hydrodynamic torque converter comprising rotatable and bladed inputrotor means, rotatable and bladed output rotor means, rotatable andbladed stator means, a ground member, an engageable and disengageablefriction device for connecting and disconnecting said rotatable statorand said ground member, said friction device having first and secondfriction members, said bladed stator means being operatively secured tosaid first friction member, each of said friction members having afriction surface, said friction surfaces being disposed adjacent co eachother, mounting means securing said second member to said ground sleeve,mounting means for mounting said first friction member for axial slidingmovement relative to said second friction member to cause the engagementand disengagement of said friction surfaces of said friction members sothat the net sum of the axial forces applied by the circulating fluidwithin said converter to the blades of said stator causes the frictionalengagement of said friction surfaces under torque multiplying operatingconditions of said converter to produce a rotary reaction force so thatsaid stator will be connected to ground and multiply the torque appliedto said input member and subsequently so that the net sum of the axialforces is reduced to zero at the same time as the rotary reaction forceis reduced to zero when the rotary speed of said output rotor meansapproaches the rotary speed of said input rotor means thereby providingfor the free rotation of said stator means in said converter withoutdelay or resistance.

4. A hydrodynamic torque converter comprising rotatable pump meanshaving a plurality of blades, rotatable turbine means having a pluralityof blades, rotatable and axially movable stator means, said pump means,said turbine means and said stator means being arranged in a torus tocirculate fluid therein in response to rotation of said pump means, aground member, a single friction unit for connecting said bladed statorto said ground member in response to the rotation of said pump meansrelative to said turbine means and until said turbine means acceleratesfrom zero up to approximately the speed of said turbine means, saidfriction unit comprising first friction means fixed to said groundmember and second friction means adjacent to said first friction meansfixed to said stator means, said stator means having blade means withfluid directing faces that direct the fluid exiting from said turbinemeans into said pump means from converter stall up to converter couplingand convert a part of the force from fluid circulated through saidstator means into an axial force to effect axial movement of said statormeans and the frictional engagement of said first and second frictionmeans, said blades being disposed on said stator so that said axialforce gradually diminishes to zero as said turbine means approaches thespeed of said pump means to effect the disengagement of said frictionmeans to thereby permit said stator to rotate with said circulatingfluid so that said converter enters the coupling phase of operation.

1. In a hydrodynamic torque transmitting unit having a plurality ofbladed rotors which are rotatable about a longitudinal axis, an inputoperatively connected to a first of said rotors, an output operativelyconnected to a second of said rotors, a third of said rotors operativelydisposed in said unit between said first and second rotors, a groundsleeve extending into said unit, friction means for connecting anddisconnecting said third rotor and said ground sleeve, said frictionmeans comprising first and second friction members, said first frictionmember having a conical friction surface thereon and having a supportsleeve extending longitudinally therefrom, said second friction memberbeing mounted for rotary and longitudinal movement with respect to saidlongitudinal axis on said support sleeve, said second friction memberhaving a conical friction surface thereon for frictionally engaging saidfirst mentioned friction surface, connecting means for connecting saidsecond friction member and said third rotor so that the force ofconverter fluid circulating in said converter acting on said third rotorin a first operating condition will effect the limited longitudinalmovement of said second friction member in one direction and theengagement of said friction surfaces to thereby ground said third rotorand so that the friction surfaces disengage without substantial dragpermitting rotation of said third rotor in response to the removal ofsaid fluid forces as said second rotor reaches approximately the speedof said first rotor.
 2. The torque transmitting unit of claim 1 andfurther comprising spring means operatively disposed between saidfriction members for exerting an axial force on said second frictionmember to cause the rapid disengagement of said friction surfaces as therotary speed of said second rotor is substantially equal to the rotaryspeed of said first rotor so that said third rotor is released for freerotation in said hydrodynamic unit.
 3. A hydrodynamic torque convertercomprising rotatable and bladed input rotor means, rotatable and bladedoutput rotor means, rotatable and bladed stator means, a ground member,an engageable and disengageable friction device for connecting anddisconnecting said rotatable stator and said ground member, saidfriction device having first and second friction members, said bladedstator means being operatively secured to said first friction member,each of said friction members having a friction surface, said frictionsurfaces being disposed adjacent co each other, mounting means securingsaid second member to said ground sleeve, mounting means for mountingsaid first friction member for axial sliding movement relative to saidsecond friction member to cause the engagement and disengagement of saidfriction surfaces of said friction members so that the net sum of theaxial forces applied by the circulating fluid within said converter tothe blades of said stator causes the frictional engagement of saidfriction surfaces under torque multiplying operating conditions of saidconverter to produce a rotary reaction force so that said stator will beconnected to ground and multiply the torque applied to said input memberand subsequently so that the net sum of the axial forces is reduced tozero at the same time as the rotary reaction force is reduced to zerowhen the rotary speed of said output rotor means approaches the rotaryspeed of said input rotor means thereby providing for the free rotationof said stator means in said converter without delay or resistance.
 4. Ahydrodynamic torque converter comprising rotatable pump means having aplurality of blades, rotatable turbine means having a plurality ofblades, rotatable and axially movablE stator means, said pump means,said turbine means and said stator means being arranged in a torus tocirculate fluid therein in response to rotation of said pump means, aground member, a single friction unit for connecting said bladed statorto said ground member in response to the rotation of said pump meansrelative to said turbine means and until said turbine means acceleratesfrom zero up to approximately the speed of said turbine means, saidfriction unit comprising first friction means fixed to said groundmember and second friction means adjacent to said first friction meansfixed to said stator means, said stator means having blade means withfluid directing faces that direct the fluid exiting from said turbinemeans into said pump means from converter stall up to converter couplingand convert a part of the force from fluid circulated through saidstator means into an axial force to effect axial movement of said statormeans and the frictional engagement of said first and second frictionmeans, said blades being disposed on said stator so that said axialforce gradually diminishes to zero as said turbine means approaches thespeed of said pump means to effect the disengagement of said frictionmeans to thereby permit said stator to rotate with said circulatingfluid so that said converter enters the coupling phase of operation.